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Chronic L-DOPA administration is not toxic to the remaining dopaminergic nigrostriatal neurons, but instead may promote their functional recovery, in rats with partial 6-OHDA or FeCl(3) nigrostriatal lesions. In this study, we have examined the effects of chronic L-3,4-dihydroxyphenylalanine (L-DOPA) administration on the remaining dopaminergic neurons in rats with 6-hydroxydopamine (6-OHDA) or buffered FeCl(3) partial lesions to the nigrostriatal tract. L-DOPA administration increased the turnover of dopamine in the striatum. L-DOPA administration for 1 week produced an increase in the level of striatal RTI-121 binding, a specific marker for dopamine uptake sites on the dopaminergic nerve terminals in the striatum. However, longer periods of L-DOPA treatment decreased the level of RTI-121 binding in the striatum. In the partial 6-OHDA lesion model, L-DOPA treatment had a time-dependent effect on the number of neurons demonstrating a dopaminergic phenotype i.e., neurons that are tyrosine hyrdoxylase (TH)-immunopositive, on the lesioned side of the brain. In the first few weeks of treatment, L-DOPA decreased the number of TH-positive neurons but with long-term treatment, i.e., 24 weeks, L-DOPA increased the number of neurons demonstrating a dopaminergic phenotype. Even in the buffered FeCl(3) infusion model, where the levels of iron were increased, L-DOPA treatment did not have any detrimental effects on the number of TH-positive neurons on the lesioned side of the brain. Consequently, chronic L-DOPA treatment does not have any detrimental effects to the remaining dopaminergic neurons in rats with partial lesions to the nigrostriatal tract; indeed in the 6-OHDA lesion model, long-term L-DOPA may increase the number of neurons, demonstrating a dopaminergic phenotype. Copyright 2001 Movement Disorder Society. PMID: 11391735 [PubMed - in process] Datla KP, Blunt SB, Dexter DT. Parkinson's Disease Research Unit, Department of Neuroinflammation, Imperial College School of Medicine at Charing Cross Campus, London, United Kingdom. 1: Mov Disord 2001 May;16(3):424-34 http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list _uids=11391735&dopt=Abstract janet paterson: an akinetic rigid subtype, albeit perky, parky . pd: 54/41/37 cd: 54/44/43 tel: 613 256 8340 email: [log in to unmask] . snail mail: 375 Country Street, Apt 301, Almonte, Ontario, Canada, K0A 1A0 . a new voice: the nnnewsletter: http://groups.yahoo.com/group/janet313/ . a new voice: the wwweb site: http://www.geocities.com/janet313/ . ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn